Do cannas bulbs rot the soil around them?

What happens if you leave Cannas bulbs in the ground? Does their rotting create any kind of disease or harm to the soil and growth around it?

If you live in an area that has hard freezes in winter, the bulbs (more properly rhizomes) are killed and they decompose and nurture the soil, improving it. If the winters are mild, they will begin growing in the spring.
Hope this helps. Good Luck!

No. makes for a good compost.